A. Field of the Invention
The present invention is generally directed to air pressure valves and gauges, and more particularly to a tire valve and core possessing a built-in calibrated air pressure regulator and an optional integrated air pressure indicator.
B. Brief Description of Related Art
Maintaining proper tire pressure is important to achieving optimum vehicular performance and minimizing operating costs. Vehicles with over- or under-inflated tires generally suffer from impaired braking and handling (e.g.. front-end shimmy, pulling to one side). This in turn poses a safety risk since the vehicle may not corner or decelerate effectively. Indeed, it is estimated that under-inflated tires contribute to approximately 260,000 accidents per year. Additionally, many motorists get stranded on busy highways and deserted rural roads due to blowouts partially caused by improperly inflated tires.
Improper inflation also results in accelerated tire tread wear and increased fuel consumption. Industry studies show that fuel savings of 5% or more are achievable when tires are run at their proper operating pressure. Furthermore, maintaining proper tire pressure can provide 20% more miles of tread life. Consequently, proper tire inflation saves the user money as well as being beneficial to the environment by reducing fossil fuel consumption, emissions, and the number of used tires that need to be disposed. Additionally, individuals often spend unnecessary time and money believing that they need car repairs, such as an alignment, when in actuality their tires are improperly inflated.
Standard tire valve stems simply house a valve that allows air to flow into and out of the tire. These existing valve stem mechanisms neither regulate nor measure and display the tire's air pressure to the user. Indeed, a separate tire pressure gauge must be employed to ascertain a tire's pressure, and this measurement must be compared with the manufacturer's recommendation. This requires extra effort on the part of motorists who are often unaware or unconcerned about the significance of proper tire inflation. Also, if the tire pressure gauge is not used or calibrated correctly, the user may inadvertently release air pressure from the tire or the pressure measurement may be incorrect, thereby exacerbating attempts to achieve the recommended pressure. Furthermore, many motorists do not check their tire pressure regularly and many may not even know how to locate the manufacturer's recommendation.
Wu, U.S. Pat. No. 5,103,670, teaches a pressure gauge incorporated into the tire stem and actuated by a mechanical bellows whose motion is then translated into a rotational displacement for the pressure indicator. The device fails to address the need for automatic air pressure regulation.
Van Heuval (U.S. Pat. No. 2,569,120), Hunt (U.S. Pat. No. 4,924,697), and Guy (U.S. Pat. No. 3,592,218) disclose tire air pressure gauges that are mounted onto a tire's existing valve stem. These devices do not directly integrate the pressure indicator into the valve stem mechanism nor do they address the need for automatic air pressure regulation.
Weaver, U.S. Pat. No. 1,590,141, teaches a pressure gauge integrated within the tire's valve stem. The device utilizes a glass U-tube filled with liquid glycerin to measure the pressure within the tire. This device does not address the need for automatic pressure regulation. Furthermore, the use of liquid-filled glass tubes makes for questionable durability in automotive use.
Many of these devices do not allow for the quick and facile release of tire pressure as is needed when changing tires; have very complicated designs; and would not be interchangeable with valve stems currently on the market, such as the Shrader valve stem.
The most common valve stem and incorporated into the majority of tires on the market today is known as the Shrader valve stem. The Shrader valve stem was patented in the late 19.sup.th century. Currently known inflation and deflation devices tend to be rather complicated and are typically not interchangeable with the current Shrader valve core. Therefore, when their use is desired, the valve stem and core must replace an existing shrader valve stem and core. Furthermore, the valve stem and core must also be made inexpensively enough to be economically feasible for the buyer.
For example, DeVuyst, U.S. Pat. No. 5,694,969, discloses a tire valve with separate inflation and deflation devices incorporated in one stem. The deflation device uses a ball valve in conjunction with a hole cut into the side of the valve stem body. Unfortunately, the design of this valve stem is complicated and it would apparently not be interchangeable with the current Shrader valve core that is used on most tires.
Keys, U.S. Pat. No. 4,883,107, uses a central spring and pin design for tire inflation and a concentrically aligned outer spring for releasing excess tire pressure, both housed within the valve stem body. This design requires a significantly different valve stem body design that will not be interchangeable with the current Shrader valve core. Also, the user or installer must set the spring to a particular p.s.i. using a screw-in cap. This must be done each time this valve is replaced. Besides this, the screw-in cap is not locked down in any way. So, the cap may unscrew during use and defeat the whole purpose of the design.
Moore, U.S. Pat. No. 5,365,967, teaches a valve stem design that uses a ball valve design with a reeded air porting scheme. This design is complicated and would also not be interchangeable with the current Shrader valve core.
Klink, U.S. Pat. No. 5,325,886, and Wu, U.S. Pat. No. 5,103,670, disclose a valve stem that uses a built in valve gauge to tell the end user the pressure in the tire. This design does not automatically release excess tire pressure.
Tuan et al., U.S. Pat. No. 5,054,511, teaches a tire valve that uses one ball valve to allow air into the tire and another ball valve to release excess tire pressure through a hole drilled into the side of the valve stem body. This design is inconsistent with and would require a dramatic change in the Shrader valve stem.
Gould, U.S. Pat. No. 4,991,618, teaches a tire valve that uses four different spring structures working in conjunction to shut off the tire valve once the tire reaches the desired pressure. This large, complicated design does not release excess tire pressure and therefore does not address the need for releasing air from an over-inflated tire.
Keys, U.S. Pat. No. 4,869,306, discloses a tire valve that uses a central pin design in order to allow air into the tire and an offset spring design attached to the side of the valve stem body that releases excess air pressure through a hole in the side of the valve stem body. This design would require a dramatic change in the Shrader valve stem design and would not be interchangeable with the current Shrader valve core.
Zeyra, U.S. Pat. No. 4,134,424, discloses a tire valve that uses a Shrader valve core to allow air into the tire and an elastic membrane to allow excess air pressure to escape through a long tube running parallel to the longitudinal axis of the valve stem body. This design would require a dramatic change in the Shrader valve stem design and would not be interchangeable with the current Shrader valve core.
Wanstreet, U.S. Pat. No. 4,015,623, discloses a tire valve having two separated devices set up in a smoke stack type design. One device is used to inflate the tire. The other is used to release excess tire pressure. This design would require a dramatic change in the Shrader valve stem design and would not be interchangeable with the current Shrader valve core.
Thus, there is an identifiable need for providing a simple mechanism that would be interchangeable with currently-marketed valve stem cores and housings to assist individuals in measuring and maintaining proper tire pressure in order to ensure prolonged tire life, optimal energy efficiency, safe handling, lowered emissions, and decreased automobile maintenance. However, such a simple and easy mechanism or device to aid motorists in achieving proper tire inflation is currently unavailable, particularly a device that would allow for the quick and facile release of tire pressure, e.g. to assist tire retailers in rapidly changing tires.